Definition of Sign language

Sign language: A language
that employs signs made with the hands and other movements, including facial
expressions and postures of the body, used primarily by people who are deaf.
There are many different sign languages as, for example, British and American sign languages. British sign language (BSL) is not easily intelligible to users of American sign language (ASL).
Unlike ASL, BSL uses a two-handed alphabet. In developing countries, deaf people
may use the sign language of educators and missionaries from elsewhere in the
world. For example, some deaf individuals in Madagascar use Norwegian sign
language. By contrast, deaf children in Nicaragua have created their own sign language. Study of the emerging Nicaruagan sign language (NSL) has revealed that children naturally possess learning abilities capable of giving language its fundamental structure. See also: American sign language.